The Decibel Scale.
Get a sense of the perceptual significance of the decibel scale by
hearing sequences of tones differing by different numbers of decibels.

The encoding of frequency

The Place Theory. See
how different frequencies impact the travelling wave which forms the
basis of place theory.

Frequency Theory.
See how the frequency of a stimulus is related to the firing rate of a
single neuron which forms the basis of frequency theory.

Volley Principle.
Illustration of how having multiple neurons allows the encoding of
higher frequency tones in Frequency Theory.

Masking

Tone Masking.
Examine what it takes for one tone at one frequency to block the
perception of a tone at another frequency. this is called Tone
Masking. It turns out that it is easier to for a tone of a lower
frequency to mask a tone of a higher frequency than in the opposite
situation.

The Ear and Tone
Masking. See an illustration of how tone masking works by
viewing the impact of two tones on the motion of the basilar membrane in
the cochlea.